Why Are My Aquarium Plants Turning Yellow?

Why Are My Aquarium Plants Turning Yellow?

If you find your aquarium plant are changing their color from green to yellow, here are the 10 reasons for the discoloration and their solutions.

Why Are My Aquarium Plants Turning Yellow? Yellowing of the aquarium plants is a common problem and an indicator of certain nutritional deficiencies and maintenance failure. Aquarium plants may lose or change their original color and start turning yellow-brown due to lack of nutrition, diseases, poor quality of water, insufficient light, and lack of carbon dioxide. They may ultimately turn red or even darker and results in plant death in the end.

Why Are My Aquarium Plants Turning Yellow?

Maintaining a thriving planted tank is not easy as it requires experience and knowledge regarding every species you choose to add to it. Live green aquarium plants add so much beauty and class to your aquarium.

Aquarium plants need favorable environmental conditions and also adequate nutrients to thrive and grow. They can not thrive or grow unless you provide them all their basic needs. Unfortunately, many people establish a tank but do not understand the concern and dedication they need to invest to ensure its maintenance.

You may experience several issues while cultivating the aquarium plants but do not worry because you only have to know the appropriate methods and remedies to reverse the damage and issues. Yellowing is one of the main plant problems and is generally the first sign of imbalance or deficiency.

Green aquarium plant is turning yellow

Green plants of your aquarium may turn yellow when you do not provide the necessary factors for their survival. This change in color tells you that your plant is unhealthy and can eventually die if you neglect the issue.

Yellowing of chlorosis is a concern of hobbyists and aqua-spacers as it requires recognition of the main reason behind it. The discoloration of plants looks extremely bad and leaves you with an unhealthy tank.

Insufficient supply of light

Aquarium plants are living organisms that require light to produce energy through photosynthesis and to facilitate other biological processes. When your tank has no or inadequate light, the leaves start changing their color from green to yellow.

Insufficient light is the most common reason behind the discoloration of your tank’s plant. Other consequences of inadequate light are weak and small leaves, thin stems, slow growth, and death of the plant.

Aquarium plants turn yellow due to nutrient deficiency

The nutrients are the requirement of both plants and animals, and plants can not survive or grow in the absence or deficiency of required nutrients. When you do not provide nutrients to them, they start rotting and turning yellow. 

When you observe a strange pattern like the veins remain green, but the tissues turn yellow, it is a nutrient deficiency. There are some essential nutrient can helps your plant grow healthy, and their absence causes discoloration:

Nitrogen deficiency

Nitrogen is essential for aquatic plants, and they absorb them in many forms such as ammonia, urea, nitrate. Failure in the maintenance of optimal nitrogen level can cause yellow coloring of the plant leaves, especially in older plants.

Not only discoloration, increase in smaller new leaves or cripples growth are also indicators of nitrogen deficit. Also, the production of algae due to nitrogen deficiency further destroys the health of plants and fish.

Lack of Potassium

A symptom of potassium deficiency is the yellowing of leaves and black spots that grow into holes in plant leaves. If it continues, the plant may stop growing and result in a stunted plant.

Also, some plants like java fern and anubias grow in an environment containing more potassium levels. So, they can turn yellow in a low potassium environment. Leave the aquarium plants in the pots for better results.

Lack of Magnesium

Magnesium has a role in photosynthesis, and it is a part of the plant’s color pigment or chlorophyll.

This nutrient is essential for the green color of leaves, and its deficiency leads to pale or yellow discoloration. The yellow coloration occurs in the tissues while leaf veins remain green, and sometimes the leaf edges may also droop.

Phosphorous deficiency

Phosphate is a nutrient that plants consume in high amounts like nitrogen, and its deficiency affects mostly older leaves. Its leaves can change color to yellow with soggy brown patches. Algae spots also form on leaves resulting in dying leaves.


Sulfur deficiency is another reason behind the discoloration, and it begins with the newest leaves, extending throughout the plant.


The aquatic plants require iron in small amounts for optimal growth and production of chlorophyll. When the plant is iron deficient, it can not produce sufficient chlorophyll in the new shoots. The lack of iron leads to fading and paleness of leaves and turning them yellow to white color.

In addition to discoloration, severe iron deficiency can lead to stunted plant growth and black leaves that can ultimately die.

Due to Over-fertilizing the tank

Fertilizers help increase the growth rate of aquarium plants but are not always beneficial. When you add too many fertilizers into the tank to grow them faster, it results in toxicity. This toxicity can burn the leaves and make them yellow in appearance.

Diseases in aquarium plants

Infectious diseases are the other reason behind the discoloration of aquarium plants. The most common pathogens that affect aquarium plants are fungi and bacteria and cause yellowing. 

Bacteria and fungi get access to your tank when you do not maintain proper hygiene in the tank. These pathogens can damage the whole plant, and the first sign is the yellowing of leaves.

Poor substrate

It is necessary to recognize the correct substrate, which is suitable and favorable for your aquarium plants. If it can not supply nutrients to the plants, they may get deficient and leads to a change in plant color. However, many aquarium plants can grow without soil.

Aging of plants

Aging is a natural process that brings several deterioration processes in the plant body, and you can not reverse it. With age, aquarium plants can turn yellow because they lose the ability to absorb nutrients, and you can not control it. 

Wrong choice of aquarium plant

It is necessary to recognize the right choice of aquarium stem plants. When you put any plant into the tank without knowing if it is aquatic or not, you can damage the plant and the tank. Every plant can not adjust and adapt to the tank’s environment.

Not all plants can live underwater as some can get damage from excess water; excess moisture can turn plant yellow. When you do not know about the plant’s needs, it can deteriorate or change color.

Carbon dioxide deficiency

Carbon dioxide is the basic need of most aquatic plants, and in its absence, they can experience several damages. Yellowing of leaves and stunted plant growth are the main consequences of carbon dioxide deficiency.

Bad Water quality

Water quality affects plant health and growth, and poor-quality can lead to the yellowing of plants. The water pH, water hardness, water temperature, and other parameters can deteriorate the plant, starting from changing its color to yellow.

You have to maintain and adjusts the water temperature according to the need of plants inside the tank. The water temperature impacts the color of plant leaves and can result in yellowing. If your aquarium heater is not working, you should fix it.

In the cold temperature, the plant leaves start turning yellow. If the water temperature remains low for a long time, these yellow leaves can further darken in color and are more likely to turn brown.

Every plant requires optimum pH for its growth and color maintenance. An increase in pH decreases the required level; the plant starts turning yellow and losses its original color.

Poor drainage and cleaning of the tank

Poor drainage and contaminated water can turn the plants into a yellow color as the plant can not absorb nutrients from the water.

The contamination in water can cause blocking in the filter, which further results in the yellow color of the aquarium plants. Also, wastes and other impurities in water damage and changes the color of the plant.

How to stop aquarium plants from turning yellow?

Maintain water quality and purity

Try to keep the water clean and pure as much as possible by regular water disposal and water change. Hygiene is a necessary aspect for keeping your tank plants healthy and prevent from color change.

Keep water pH between 6.5 to 7 and water hardness between 50 ppm to 100 ppm. Maintain optimal water temperature depending upon the requirement of your tank plants. The most appropriate temperature for an aquarium ranges from 74 degrees Fahrenheit to 80 degrees Fahrenheit.

Add live beneficial bacteria or any bio media to your filter to improve water quality. It will prevent the growth and accumulation of algae.

Provide optimum lighting

As light plays a role in maintaining plants’ color, so provide sufficient light to the tank. Generally, aquarium plants require full-spectrum light for 10 to 12 hours daily. Pick a suitable light source such as LED strips or high-output fluorescent and provide 4 to 5 watts of light power per gallon of tank.

Preferable substrate texture

The best gravel or substrate for aquatic plants is fine to medium size gravel or coarse want. It is better to mix both to achieve a desirable texture. Do not go for super-fine sand to prevent compactness.

Add a sufficient amount of fertilizers

Supply all the nutrients in an adequate amount to your plants to stop aquarium plants from turning yellow. Fertilizers are the best option to maintain an optimum level of all nutrients and use liquid or powdered fertilizers because plants can better absorb them.

Optimal concentrations of the requires nutrients for aquarium plants are:

  • Nitrogen – 10 to 25mg/l
  • Iron -0.05 to mg/l
  • Potassium -10 to 50 ppm
  • Magnesium -1150 to 1350 ppm
  • Phosphate – 0.5 ppm
  • Some best fertilizers for aquarium are:
  • API leaf zone
  • Easy green or easy root tabs
  • Seachem flourish
  • Aqua soil

Add CO2 Supplements

Carbon dioxide supplements are the better choice to ensure their sufficiency. Use liquid or tablets, and you can also use homemade yeast generators. You can also add a carbon dioxide pump to the tank for a daily dose.

The desired carbon dioxide level in the tank should be 20 to 30mg/l, and monitor the concentration with a drop-checker.

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